The current proliferation of front wheel drive vehicles with liquid-cooled engines mounted transverse to the longitudinal axis of the vehicle has complicated traditional cooling fan drive arrangements wherein the engine is mounted parallel to the longitudinal axis of the vehicle. Vehicles with either longitudinally or transversely mounted engines preferably have the radiator positioned forwardly of the engine and in a plane transverse to the longitudinal axis since such positioning provides direct access for ambient air flow through the radiator, particularly ram air, and since space for the radiator is readily provided with such positioning.
In vehicles with longitudinally mounted engines, forwardly mounted radiators, and axial flow fans mounted between the engines and the radiators, the axial flow fans are conveniently mounted on the front of the engines with their rotational axes parallel to the engine crankshaft axes and are readily driven by mechanical drives, such as belts driven by pulleys mounted on forward projections of the engine crankshafts. Such arrangements are simple, reliable, relatively inexpensive, and last, but not least, relatively efficient. In vehicles with transversely mounted engines, forwardly mounted radiators, and axial flow fans mounted between the engines and the radiators, the axial flow fans cannot, as a practical matter, be mounted on the engines with their rotational axes parallel to the engine crank-shaft axes and cannot be readily driven by mechanical drives, such as belts driven by pulleys mounted on projections of the engine crankshafts. Hence, vehicles with transversely mounted engins and radiators positioned forwardly of the engines, for the most part, now use electric motors to drive the fans. The electric motors are in general more expensive than the mechanically driven fans and are believed to be less reliable. Further, since the electric motors are price sensitive per unit of horsepower and substantially less efficient than mechanical drives, some vehicle manufacturers have increased the size of the radiators to reduce the motor size and have spent considerable time developing more efficient axial flow fans to further reduce motor size.
One prior art reference, U.S. Pat. No. 3,696,730 issued Oct. 10, 1972, schematically discloses a transverse engine vehicle with a forwardly mounted radiator and several embodiments of mechanically driven fans. One embodiment discloses a centrifugal fan with axial inlet and radial outlet mounted on one end of the engine. The other embodiments disclose axial flow fans transversely disposed with respect to one end of the engine and with the rotational axes of the fans either in line with the engine crankshaft axis or forward thereof. All of these embodiments require transverse offsetting of the radiators and/or the engines, transverse offsetting of the fans, bulky ducts for directing air to and from the fans, and tortuous flow paths for the air. Transverse offsetting of the radiators, though possible even in relatively small cars, is not desirable since it interferes with headlight and fender mountings unless the front of the vehicle is extended to provide additional room. Transverse offsetting of transversely mounted engines is undesirable since it upsets vehicle weight distribution and, as a practical matter, there is insufficient transverse space for such offsetting in passenger vehicles with forwardly mounted transverse engines. Likewise, there is insufficient transverse space for transverse offsetting or positioning of the fans at one end of the engines. Further, the bulky or large ducts for directing the air to and from the fans would at best be difficult to install in the limited space available in such vehicles.